You'd be surprised how little you *can* get away with eating on for a 200...
Today I did a 200k DIY. On the train to Enschede I had a baguette (about 250mm long), with 2 slices of cheese, a large cookie, and a packet of crisps. at 50km I had some fries with ketchup, and a can of coke, 100k in I had some M&M's and some "Crisp cheese savories" maybe half a handful of each. At 125k I had a slice of apple pie, and 400ml of fanta. At 180k I had a small handful of M&M's. and over the day I drank a 500ml bottle of coke. Total M&M consumption was 107gm.
My wahoo/strava think I burned ~4500kcal. I think I consumed about 2500kcal. but I'd need to do the maths more to be sure. I'm hungry now, but I'm not ravenously hungry. I was slow in the last 20k or so, but that's cos I came into the city...
Last April I had an ill-advised collision with flying insect, which resulted in a triggered gag reflex, and dumping of my stomach contents. I was 150km into a 300k Audax. My stomach refused to accept solid food, and I did the last 150k on about 600ml of coke.
If you have started the day with a full complement of glycogen (about 2000kcal), you've got enough energy to do most of the first 100k, as long as you drink enough water (your body needs water to burn glycogen).
I've been trying to lose weight, and have been doing so through cycling, a lot. I'm kinda used to being hungry on a bike ride... I may be faster if I ate better...
Anyway, the plural of anecdote is data...
J